Heretofore there is known an electronic apparatus constructed of an electronic device mounting substrate with an electronic device mounted thereon. As the electronic device mounting substrate used for such an electronic apparatus, there is known one comprising a metallic base body and a frame-shaped wiring substrate. To construct the electronic apparatus, an electronic device is mounted on the electronic device mounting substrate, and, a lid body is disposed on the upper surface of the wiring substrate. In the electronic apparatus thereby constructed, the electronic device is mounted in a recess defined by the upper surface of a thermal diffusion metallic layer disposed on the upper surface of the metallic base body and the inner side surface of the frame-shaped wiring substrate, and, an external circuit and so forth are electrically connected to an external circuit connection electrode disposed on a surface of the wiring substrate such as the upper surface thereof (refer to Japanese Unexamined Patent Publication JP-A 2006-303400).
Higher and higher performance capabilities have been demanded in portable terminal equipment as typified by smartphones, information processing equipment as typified by PCs (Personal Computers), and digital home-use appliances as typified by digital cameras, and, in order to respond to such a demand, it is necessary to mount a larger number of electronic apparatuses in a single housing. However, housings can no longer be given an increased capacity, wherefore housing capacity inevitably remains at its present level, or, on the contrary, it has come to be reduced. This trend has created the necessity of downsizing and low-profile design of electronic apparatuses. In the case of the electronic apparatus described in JP-A 2006-303400, it is conceivable that the thickness of the metallic base body of the electronic device mounting substrate will be reduced to render the electronic apparatus lower in profile.
In this electronic apparatus, when the lid body is subjected to an impact, a stress is applied to the wiring substrate. However, if the metallic base body has a reduced thickness for low-profile design of the apparatus, the applied stress will cause warpage or fracture in the wiring substrate. After all, it is not easy to achieve the low-profile design by the reduction of the thickness of the metallic base body.
An object of the invention is to provide an electronic device mounting substrate and an electronic apparatus which are capable of enhancement in impact resistance.